Thermoplastic resin composition having excellent long-term heat-aging properties

ABSTRACT

The present invention relates to a thermoplastic resin composition with excellent long-term heat-aging properties, comprising:  
     (I) 10 to 45% by weight of a rubber-modified thermoplastic resin obtained by graft polymerizing at least one monomer selected from the group consisting of aromatic vinyl compounds, vinyl cyanide compounds and other vinyl monomers copolymerizable therewith in the presence of a rubber-like polymer;  
     (II) 5 to 30% by weight of a thermoplastic resin obtained by copolymerizing the monomers comprising an aromatic vinyl compound, a vinyl cyanide compound and optionally other vinyl monomer copolymerizable therewith; and  
     (III) 50 to 70% by weight of a polycarbonate resin, the content of the vinyl cyanide compound in the whole produced composition being 3 to 12% by weight.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a thermoplastic resincomposition having excellent long-term heat-aging properties. Moreparticularly, it relates to a thermoplastic resin composition havingexcellent impact resistance, heat resistance, chemical resistance andweather resistance, and further remarkably improved in long-termheat-aging properties.

[0002] Polycarbonate (PC) resins have excellent heat resistance andmechanical properties, the molded products thereof are excessivelyreduced in impact strength when they are flawed because of high notchsensitivity. PC resins also have a disadvantage that it is necessitatedto set the molding temperature in a high range due to too high heatresistance, so that they are inexpedient for molding of large-sizedarticles.

[0003] On the other hand, ABS resins (acrylonitrile-butadiene-styreneresins) are a material having a good balance of properties such asmoldability, impact strength and dimensional stability, and widely usedfor a variety of commercial products such as automobiles, domesticelectrical appliances, OA machines, etc., but they have a disadvantagethat they are low in heat resistance. Japanese Patent Publication(KOKOKU) No. 38-15225 proposes blending of a PC resin with an ABS resinhaving good compatibility with the PC resin to thereby improve suchproperties as notched impact strength, molding workability and heatresistance. The PC resin/ABS resin polymer alloys (which may hereinafterbe referred to as “PC/ABS polyblends”) are now one of the typical resincompositions popularly used in the fields of OA machines, vehicles andsuch.

[0004] Another drawback to the ABS resins is poor weather resistance dueto use of butadiene rubber. Japanese Patent Publication (KOKOKU) No.51-24540 proposes polyblending of a PC resin and an AES resin usingethylene-propylene (EP) rubber to improve stain resistance. JapanesePatent Publication (KOKOKU) No. 1-57699 proposes addition of a specificplasticizer to the PC resin/AES resin polymer alloys (which mayhereinafter be referred to as “PC/AES polyblends”) to improve weldstrength. Further, Japanese Patent Publication KOKOKU) No. 3-40064proposes optimization of the rubber content, graft ratio and molecularweight of the PC/AES polyblends to improve weld appearance and coatingproperties. Japanese Patent Publication (KOKOKU) No. 1-17501 proposespolyblending of the three types of resin, i.e. PC resin, ABS resin andAES resin, to improve low-temperature impact strength, weld strength andcolor development. Japanese Patent Publication (KOKOKU) No. 4-29696proposes addition of α-alkylstyrene as the graft resin component of thePC/AES polyblends to improve thermal decomposability in the course ofgranulation and molding work. Japanese Patent Publication (KOKOKU) No.4-56063 proposes optimization of melt viscosity of the AES resin in thePC/AES polyblends to improve weld strength. Japanese Patent Publication(KOKOKU) No. 5-79699 proposes optimization of the rubber content of thePC/AES polyblends to improve low-temperature impact strength.

[0005] As viewed above, since the PC/ABS and PC/AES polyblends haveexcellent properties, various use for them are found. But when theseresins once molded into a product are exposed to high temperatures for along time in a practical use environment, their properties aredeteriorated drastically. This is attributable to such causes asdeterioration of the PC resin, deterioration of the grafted or ungraftedresin and deterioration of the rubber, but no proposal of the attemptfor solving these problems has ever been made in the past.

[0006] As a result of the present inventors' earnest studies to solvethe above problems, it has been found that a thermoplastic resincomposition comprising a specific rubber-modified thermoplastic resin, aspecific thermoplastic resin, a polycarbonate resin and a heat-agingresistor, with the content of vinyl cyanide compound in the wholecomposition being defined, has excellent long-term heat-agingproperties.

[0007] The present invention has been attained on the basis of the abovefinding.

SUMMARY OF THE INVENTION

[0008] The object of the present invention is to provide a thermoplasticresin composition having excellent long-term heat-aging properties aswell as high impact strength and heat resistance by adding a specificthermoplastic resin to a polymer alloy of a polycarbonate resin and arubber-modified thermoplastic resin.

[0009] To attain the above aim, in the first aspect of the presentinvention, there is provided a thermoplastic resin composition withexcellent long-term heat-aging properties, comprising:

[0010] (I) 10 to 45% by weight of a rubber-modified thermoplastic resinobtained by graft polymerizing at least one monomer selected from thegroup consisting of aromatic vinyl compounds, vinyl cyanide compoundsand other vinyl monomers copolymerizable therewith in the presence of arubber-like polymer,

[0011] the graft ratio of the polymerizate being 10 to 100% and theintrinsic viscosity η of the methyl ethyl ketone solubles at 30° C.being 0.2 to 0.8 dl/g;

[0012] (II) 5 to 30% by weight of a thermoplastic resin obtained bycopolymerizing the monomers comprising an aromatic vinyl compound, avinyl cyanide compound and optionally other vinyl monomercopolymerizable therewith,

[0013] the weight ratio of aromatic vinyl compound/vinyl cyanidecompound/other vinyl monomer being 50-90/10-20/0-30, and the intrinsicviscosity η of the methyl ethyl ketone solubles at 30° C. being 0.3 to0.6 dl/g; and

[0014] (III) 50 to 70% by weight of a polycarbonate resin,

[0015] the total amount of (I), (II) and (III) being 100% by weight, and

[0016] the content of the vinyl cyanide compound in the whole producedcomposition being 3 to 12% by weight.

[0017] In the second aspect of the present invention, there is provideda tthermoplastic resin composition with excellent long-term heat-agingproperties, comprising:

[0018] (I) 10 to 45% by weight of a rubber-modified thermoplastic resinobtained by graft polymerizing at least one monomer selected from thegroup consisting of aromatic vinyl compounds, vinyl cyanide compoundsand other vinyl monomers copolymerizable therewith in the presence of arubber-like polymer,

[0019] the graft ratio of the polymerizate being 10 to 100% and theintrinsic viscosity I of the methyl ethyl ketone solubles at 30° C.being 0.2 to 0.8 dl/g;

[0020] (II) 5 to 30% by weight of a thermoplastic resin obtained bycopolymerizing the monomers comprising an aromatic vinyl compound, avinyl cyanide compound and optionally other vinyl monomercopolymerizable therewith,

[0021] the weight ratio of aromatic vinyl compound/vinyl cyanidecompound/other vinyl monomer being 50-90/10-20/0-30, and the intrinsicviscosity η of the methyl ethyl ketone solubles at 30 ° C. being 0.3 to0.6 dl/g;

[0022] (III) 50 to 70% by weight of a polycarbonate resin; and

[0023] (IV) 0 to 2% by weight of a heat-aging resistor,

[0024] the total amount of (I), (II), (III) and (IV) being 100% byweight, and

[0025] the content of the vinyl cyanide compound in the whole producedcomposition being 3 to 12% by weight.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The rubber-modified thermoplastic resin (I) used in the presentinvention can be obtained by graft polymerizing at least one monomerselected from the group consisting of aromatic vinyl compounds, vinylcyanide compounds and other vinyl monomers copolymerizable therewith inthe presence of a rubber-like polymer. The graft ratio of thepolymerizate is 10 to 100%, and the intrinsic viscosity [η] of themethyl ethyl ketone solubles at 30° C. is 0.2 to 0.8 dl/g.

[0027] The rubber-like polymers usable for the preparation of therubber-modified thermoplastic resin (I) include, for example,polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrilecopolymer, ethylene-propylene-(nonconjugated diene) copolymer,ethylene-butene-1-(nonconjugated diene) copolymer, ethylene/hexenecopolymer, ethylene/octene copolymer, isobutylene-isoprene copolymer,acrylic rubber, styrene-butadiene-styrene block copolymer,styrene-isoprene-styrene block copolymer, hydrogenated diene-based(block, random or homo) polymers such as SEBS, polyurethane rubber, andsilicone rubber. In case of using silicone rubber, if a graftcrosslinking agent (such as the one containing a vinyl group,γ-methacryloxypropylmethyldimethoxysilane or the like) is contained inthe silicone rubber in an amount of about 0.01 to 10% by weight, therecan be obtained a thermoplastic resin composition of the presentinvention with excellent impact resistance.

[0028] The rubber-like polymer used in the present invention ispreferably selected from ethylene-propylene rubber,ethylene-propylene-nonconjugated diene rubber, acrylic rubber andsilicone rubber, more preferably selected from ethylene-propylene rubberand ethylene-propylene-nonconjugated diene rubber. Examples of thenonconjugated dienes usable here include alkenyl norbornenes, cyclicdienes, aliphatic dienes and the like, of which5-ethylidene-2-norbornene and dicyclopentadiene are preferred. Thesenonconjugated dienes may be used singly or as a mixture of two or moreof them.

[0029] The said rubber-like polymers may also be used either singly oras a mixture or composite.

[0030] By use of two or more types of graft polymer (rubber-modifiedthermoplastic resins) differing in rubber particle size, a thermoplasticresin composition with even higher impact resistance and a betterbalance of properties is obtained. It is preferred to use, for instance,two types of rubber-like polymer, one having a particle size of 800 to3,000 angstroms and the other 5.000 to 10,000 angstroms. In this case,it is possible to synthesize the graft polymers (rubber-modifiedthermoplastic resins) in the presence of two rubber-like polymersdiffering in particle size, or to blend two rubber-modifiedthermoplastic resins differing in rubber particle size.

[0031] The molecular weight of the rubber-like polymers used in thepresent invention is preferably not less than 60,000, more preferablynot less than 70,000, in terms of polystyrene-reduced weight-averagemolecular weight. When the molecular weight of the rubber-like polymersis less than 60,000, the preferred impact resistance may not beobtained. The rubber-like polymers may have a three-dimensionalcrosslinked structure.

[0032] The percentage of the rubber-like polymers in the rubber-modifiedthermoplastic resin (I) is preferably 10 to 80% by weight, morepreferably 20 to 70% by weight (feed percentage). When the saidpercentage is less than 10% by weight, the preferred impact resistancemay not be obtained, while when the said percentage exceeds 80% byweight, there may arise the problems in moldability of the compositionand visual appearance of its moldings.

[0033] The aromatic vinyl compounds usable as a monomer in therubber-modified thermoplastic resin (I) include, for example, styrene,α-methylstyrene, methylstyrene, vinylxylene, monochlorostyrene,dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene,p-t-butylstyrene, ethylstyrene and vinylnaphthalene. These compounds maybe used singly or as a mixture of two or more of them. The preferredaromatic vinyl compound for use in the present invention is styrene oran aromatic vinyl compound containing styrene in an amount of not lessthan 50% by weight.

[0034] The percentage of the aromatic vinyl compound(s) in the monomersis preferably 60 to 90% by weight, more preferably 65 to 85% by weight.

[0035] The vinyl cyanide compounds usable as another monomer includeacrylonitrile, methacrylonitrile and the like, of which acrylonitrile ispreferred.

[0036] The percentage of the vinyl cyanide compound in the monomers ispreferably 10 to 40% by weight, more preferably 15 to 35% by weight.

[0037] Other copolymerizable vinyl monomers usable for graftpolymerization in the present invention include (meth)acrylic estermonomers, for example, acrylic esters such as methyl acrylate, ethylacrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexylacrylate, octyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate andphenyl acrylate, and methacrylic esters such as methyl methacrylate,ethyl methacrylate, propyl methacrylate, butyl methacrylate, amylmethacrylate, hexyl methacrylate, octyl methacrylate, 2-ethylhexylmethacrylate, cyclohexyl methacrylate, dodecyl methacrylate, octadecylmethacrylate, phenyl methacrylate and benzyl methacrylate; unsaturatedacid anhydrides such as maleic anhydride and itaconic anhydride;unsaturated acids such as acrylic acid and methacrylic acid; andmaleimide monomers, for example, imide compounds of α, β-unsaturateddicarboxylic acids such as N-methylmaleimide, N-butylmaleimide,N-phenylmaleimide and N-cyclohexylmaleimide. Of these vinyl monomers,methyl methacrylate, N-phenylmaleimide and N-cyclohexylmaleimide arepreferred. These other vinyl monomers can be used either singly or as amixture of two or more of them.

[0038] The percentage of the said other vinyl monomer(s) in the monomermixture is preferably not more than 50% by weight, more preferably notmore than 30% by weight.

[0039] The rubber-modified thermoplastic resin (I) used in the presentinvention can be produced by the known polymerization methods such asemulsion polymerization, solution polymerization and suspensionpolymerization. In case where the resin (I) is produced by emulsionpolymerization, it is usually purified by coagulating it with acoagulant, washing the produced powder with water and drying theproduct. As the coagulant, usually an inorganic salt such as calciumchloride, magnesium sulfate, magnesium chloride, sodium chloride or thelike is used. It is to be noted that when the produced rubber-modifiedthermoplastic resin (I) is blended in a polycarbonate resin (III), theremay arise the problem of causing a reduction of molecular weight of thepolycarbonate resin (III) due to the residual salt or emulsifier in thecomponent (I). It is therefore preferable to use an acid such assulfuric acid as the coagulant.

[0040] As the radical initiator for the graft polymerization, it ispossible to use the commonly used ones, such as, for example, cumenehydropeoxide, diisopropylbenzene hydroperoxide, potassium persulfate,azobisisobutylonitrile, benzoyl peroxide, lauroyl peroxide, t-butylperoxylaurate, and t-butyl peroxymonocarbonate.

[0041] The amount of the radical initiator used is usually 0.05 to 5% byweight, preferably 0.1 to 1% by weight, based on the monomers.

[0042] The objective effect of the present invention can be obtained byproperly selecting an organic peroxide or a solvent for allowingprogress of uniform graft reaction in graft polymerization, synthesizinga rubber-like polymer by emulsion polymerization, carrying out graftpolymerization by emulsion polymerization, initiating the polymerizationby uniformly dissolving the rubber-like polymer, and designingappropriate polymerization means such as conducting solution or bulkpolymerization by dissolving the melted and kneaded monomeric mixture ina solution or conducting emulsion or suspension polymerization of there-emulsified product.

[0043] The graft ratio of the thus obtained rubber-modifiedthermoplastic resin (I) is 10 to 100%, preferably 30 to 80%. When thegraft ratio is below 10%, the interfacial adhesion strength betweenresin and rubber lowers, making it unable to obtain high impactstrength. On the other hand, when the graft ratio exceeds 100%, theinterfacial layer is enlarged in thickness and also a grafted resinlayer is created in the inside of the rubber to cause a decrease ofrubber elasticity, resulting in an unsatisfactory impact strength of thecomposition.

[0044] The said graft ratio can be easily adjusted by changing the typeand amount of the rubber-like polymer, polymerization initiator, chaintransfer agent, emulsifier, etc., and the polymerization conditions suchas polymerization time and polymerization temperature.

[0045] The “graft ratio (%)” referred to herein is the value given fromthe following equation:

Graft ratio (%)=[(y−x)/x]×100

[0046] wherein x is rubber moiety in the component (I) and y is methylethyl ketone insolubles in the component (I).

[0047] The intrinsic viscosity [η] (measured in methyl ethyl ketone at30° C.) of the methyl ethyl ketone solubles in the rubber-modifiedthermoplastic resin (I) of the present invention is 0.2 to 0.8 dl/g,preferably 0.3 to 0.7 dl/g. With the intrinsic viscosity [η] fallingwithin the above-defined range, it is possible to obtain a thermoplasticresin composition of the present invention with excellent impactresistance and molding workability (fluidity). The said intrinsicviscosity [η] can be easily controlled by changing the type and amountof the polymerization initiator, chain transfer agent, emulsifier,solvent, etc., and the polymerization conditions such as polymerizationtime and polymerization temperature.

[0048] Examples of the rubber-modified thermoplastic resins (I) usablein the present invention include ABS resins, AES resins, ASA resins(polymers obtained by grafting AS resins to acrylic rubber), and ASSresins (polymers obtained by grafting AS resins to silicone rubber). Ofthese resins, AES resins, ASA resins and ASS resins are preferred, andAES resins being especially preferred.

[0049] The percentage of the rubber-modified thermoplastic resin (I) inthe thermoplastic resin composition of the present invention is 10 to45% by weight, preferably not less than 10% and less than 45% by weight,more preferably 20 to 40% by weight based on 100% by weight of totalamount of (I), (II), (III) and (IV). When the said percentage is lessthan 10% by weight, the composition tends to have unsatisfactory impactstrength, while when the said percentage exceeds 45% by weight, fluidityof the composition and visual appearance of its moldings may bedeteriorated.

[0050] The thermoplastic resin (II) used in the present invention isobtained by copolymerizing the monomers comprising an aromatic vinylcompound, a vinyl cyanide compound and, if necessary, other vinylmonomer copolymerizable therewith. The weight ratio of aromatic vinylcompound/vinyl cyanide compound/other copolymerizable vinyl monomer is50-90/10-20/0-30, and the intrinsic viscosity [I] of the methyl ethylketone solubles at 30° C. is 0.3 to 0.6 dl/g.

[0051] The aromatic vinyl compound, vinyl cyanide compound and othervinyl monomer used in the thermoplastic resin (II) are the same as thoseused for the preparation of the rubber-modified thermoplastic resin (I)mentioned above.

[0052] The thermoplastic resin (II) used in the present invention can beproduced by known polymerization methods such as emulsionpolymerization, solution polymerization and suspension polymerization.In case where the resin (II) is produced by emulsion polymerization, itis usually purified by coagulating the polymerization product with acoagulant, washing the obtained powder with water and drying it. As thecoagulant, usually an inorganic salt such as calcium chloride, magnesiumsulfate, magnesium chloride or sodium chloride is used. It is to benoted that when the obtained thermoplastic resin (II) is blended in apolycarbonate resin (III), there may take place a reduction of molecularweight of the polycarbonate resin (III) due to the residual salt oremulsifier in the component (II). It is therefore preferable to use anacid such as sulfuric acid as the coagulant.

[0053] In the thermoplastic resin (II) used in the present invention,the ratio by weight of aromatic vinyl compound/vinyl cyanidecompound/other vinyl monomer is 50-90/10-20/0-30, preferably 72 to 85/15to 18/0 to 10. When the ratio of the aromatic vinyl compound is lessthan 50% by weight, compatibility of the resin (II) with thepolycarbonate resin (III) may lower, resulting in unsatisfactory impactstrength and heat stability of the composition. When the ratio of thearomatic vinyl compound exceeds 90% by weight, also compatibility of theresin (II) with the polycarbonate resin (III) may lower, causingdeterioration of impact strength and chemical resistance of thecomposition. When the ratio of the vinyl cyanide compound is less than10% by weight, compatibility with the polycarbonate resin (III) maylower excessively, giving rise to such problems as reduction of impactstrength and exfoliation of the surface layer, and when the ratio of thevinyl cyanide compound exceeds 20% by weight, the heat-aging propertiesof the composition may be deteriorated. It is a feature of the presentinvention that a vinyl cyanide compound is used in a defined range ofratio, i.e. 10 to 20% by weight, for markedly improving the heat-agingproperties of the composition. When other vinyl monomer is used inexcess of 30% by weight, compatibility with the polycarbonate resin(III) may deteriorate to reduce impact strength of the composition. Itis preferred that the ratio by weight of aromatic vinyl compound/vinylcyanide compound/other vinyl monomer in the thermoplastic resin (II) isdifferent from the ratio by weight of aromatic vinyl compound/vinylcyanide compound/other vinyl monomer in the thermoplastic resin (I)

[0054] The intrinsic viscosity [η] at 30° C. of the methyl ethyl ketonesolubles in the thermoplastic resin (II) according to the presentinvention is 0.3 to 0.6 dl/g, preferably 0.35 to 0.45 dl/g. When theviscosity is less than 0.3 dl/g, the produced composition may be poor inimpact strength, and when the viscosity exceeds 0.6 dl/g, thecomposition may be greatly reduced in fluidity.

[0055] The percentage of the thermoplastic resin (II) in thethermoplastic resin composition of the present invention is 5 to 30% byweight, preferably 10 to 20% by weight based on 100% by weight of totalamount of (I), (II), (III) and (IV). When the percentage of the resin(II) is less than 5% by weight, the heat-aging properties may bedeteriorated excessively, and when it exceeds 30% by weight, impactstrength of the composition may be greatly reduced.

[0056] The polycarbonate resins (III) usable for the preparation of thethermoplastic resin composition of the present invention include thoseobtained from the reactions between various dihydroxyarryl compounds andphosgene (phosgene method) and those obtained from the ester exchangereactions between dihydroxyarryl compounds and diphenyl carbonate (esterexchange method). The preferred polycarbonate resins for use in thepresent invention are the aromatic polycarbonate resins, a typicalexample of which is 2,2′-bis(4-hydroxyphenyl)propane, that is, apolycarbonate resin obtained from the reaction between bisphenol A andphosgene.

[0057] Examples of the dihydroxarryl compounds usable as a startingmaterial of the said polycarbonate resins includebis(4-hydroxyphenyl)methane, 1,1′-bis(4-hydroxyphenyl)ethane,2,2′-bis(4-hydroxyphenyl)propane, 2,2′-bis(4-hydroxyphenyl) butane,2,2′-bis(4-hydroxyphenyl)octane, 2,2′-bis(4-hydroxyphenyl)phenylmethane, 2,2′-bis(4-hydroxy-3-methylphenyl) propane,2,2′-bis(4-hydroxy-3-t-butylphenyl) propane,2,2′-bis(4-hydroxy-3-bromophenyl)propane,2,2′-bis(4-hydroxy-3,5-dichlorophenyl)propane, 1,1′-bis(4-hydroxyphenyl)cyclopentane, 1,1′-bis(4-hydroxyphenyl) cylcohexane, 4,4,-dihydroxydiphenyl ether, 4,4 ,-dihydroxy-3,3′-dimethyldiphenyl ether,4,4′-dihydroxyphenyl sulfide, 4,4′-dihydroxy-3,3 ,-dimethylphenylsulfide, 4,4′-dihydroxy-3, 3′-dimethylphenyl sulfoxide, 4,4,-dihydroxyphenyl sulfoxide, 4,4′-dihydroxyphenylsulfone, 4,4,-dihydroxy-3,3′-dimethylphenylsulfone,1,1′-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,1,1′-bis(4-hydroxyphenyl)-3,3-dimethylcyclohexane,1,1′-bis(4-hydorxyphenyl)-3,3,5-trimethylcyclopentane, hydroquinone, andresorcin. These compounds may be use singly or in combination.2,2′-bis(4-hydroxyphenyl) propane, i.e. bisphenol A, is especiallypreferred.

[0058] The viscosity-average molecular weight of the polycarbonate resin(III) is preferably 15,000 to 40,000, more preferably 17,000 to 30,000,especially preferably 18,000 to 28,000. A higher molecular weightprovides a better notched impact resistance but gives a lower fluidity.It is possible to use two or more types of polycarbonate differing inmolecular weight.

[0059] The percentage of the polycarbonate resin in the thermoplasticresin composition (III) of the present invention is 50 to 70% by weight,more preferably 55 to 65% by weight based on 100% by weight of totalamount of (I), (II), (III) and (IV). When the polycarbonate resinpercentage is less than 50% by weight, the composition may beunsatisfactory in heat resistance, and when the percentage exceeds 70%by weight, fluidity of the composition may lower excessively.

[0060] As the heat-aging resistor (IV) in the thermoplastic resincomposition of the present invention, there can be used, for instance,phenol type (phenol derivatives), phosphorus type (heat-aging resistorscontaining phosphorus), sulfur type (heat-aging resistors containingsulfur), lactone type and the like. A phenol/phosphorus/sulfurthree-type mixture is preferred. By using this three-type mixture as theheat-aging resistor (IV), the effect of enabling retention of tensileelongation can be attained when the composition is exposed to a hightemperature for a long time.

[0061] Of these heat-aging resistors (IV), the phenol type includes2,6-di-t-butylphenol derivatives, 2-methyl-6-t-butylphenol derivatives,octadecyl-3(3,5-di-t-butyl-4-hydroxyphenyl) propionate, 4,41-butylidene-bis(6-t-butyl-m-cresol),pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate],2[1-(2-hydroxy-3,5-di-t-pentylphenyl)-ethyl ]-4,6-di-t-pentylphenylacrylate, and2-t-butyl-6(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate.

[0062] The phosphorus type includes tris(2,4-di-t-butylphenyl)phosphite, cyclic neopentanetetraylbis(2,4-di-t-butylphenyl phosphite),distearylpentaerythritol diphosphite, sodium dihydrogenphosphate, anddisodium monohydrogenphosphate.

[0063] The sulfur type includes dodecyl 3,3′-thiobispropionate,octadecyl 3,3′-thiobispropionate,pentaerythritol-tetrakis-(3-laurylpropionate), and dilauryl-3,3,-thiodipropionate.

[0064] The lactone type includes 5,7-di-t-butyl-3-(3,4-dimethylphenyl)-3H-benzofuran-2-one.

[0065] The percentage of the heat-aging resistor (IV) in thethermoplastic resin composition of the present invention is 0 to 2% byweight, preferably not less than 0 but not greater than 2% by weight,more preferably not less than 0 but not greater than 1% by weight basedon 100% by weight of total amount of (I), (II), (III) and (IV). In thethermoplastic resin composition of the present invention, the resins(components (I) and (II)) other than the polycarbonate resin (III) areimproved in their heat-aging properties by the addition of a heat-agingresistor, but the polycarbonate resin may be adversely affected by theaddition of a heat-aging resistor as it might act as a catalyst whichpromotes hydrolysis. In view of these antagonistic effects, it isexpedient to add the heat-aging resistor in an amount not exceeding 2%by weight for providing a maximal heat-aging resistance.

[0066] The percentage of the vinyl cyanide compound in the thermoplasticresin composition of the present invention is 3 to 12% by weight,preferably 5 to 10% by weight. When the percentage of the vinyl cyanidecompound exceeds 12% by weight, the composition may be deteriorated inheat-aging properties, and when the percentage is less than 3% byweight, compatibility with the polycarbonate resin may lower todeteriorate impact strength of the composition.

[0067] The thermoplastic resin composition according to the presentinvention may contain if necessary one or more types of filler such asglass fiber, carbon fiber, glass beads, wollastonite, rock filler,calcium carbonate, talc, mica, glass flakes, mild fiber, barium sulfate,graphite, molybdenum disulfide, magnesium oxide, zinc oxide whiskers,potassium titanate whiskers, etc. Blending of such fillers affordsrigidity and high-temperature deformation resistance to the composition.Also, addition of talc, calcium carbonate or the like provides a matteeffect to the composition. The preferred size of the glass fibers andcarbon fibers for use in the present invention is 6 to 60 μm in diameterand 30 μm or more in length.

[0068] It is also possible to blend the known additives such asweathering agent, lubricant, colorant, antistatic agent, silicone oil,etc., in the thermoplastic resin composition of the present invention.As the weathering agent, phosphorus type, benzotriazole type, triazinetype, benzophenone type and the like are preferred. As the lubricant,ethylenebisstearylamide, hardened castor oil and the like are preferablyused. Carbon black, red oxide and the like can be used as the colorant.Polyethers and sulfonates having alkyl groups can be cited as examplesof the antistatic agent.

[0069] The thermoplastic resin composition of the present invention canbe obtained by kneading the component materials by using various typesof extruder, Banbury mixer, kneader, rolls or the like. Use of adouble-screw extruder is preferred. Regarding the way of kneading of thecomponent materials, they may be either kneaded all together or may bekneaded according to a multi-stage addition system.

[0070] The thermoplastic resin composition of the present invention maybe molded into various products by the known molding methods such asinjection molding, sheet extrusion, vacuum forming, contour extrusion,expansion molding, etc.

[0071] The thus obtained molded products can be used for variousapplications by making use of their excellent properties; for example,they can be used as disc tray material, housing material, etc., for OAmachines, domestic electrical appliances, vehicles, etc.

[0072] The thermoplastic resin composition according to the presentinvention can be used without suffering remarkable changes of propertieseven in long-time use under high temperatures, and is capable ofprolonging the life of its products and contributing to the safetythereof. The composition also has excellent fluidity and is thereforepreferred for large-sized moldings.

EXAMPLES

[0073] The present invention is described in further detail by showingits Examples and Comparative examples, but it is to be understood thatthese examples are merely intended to be illustrative and not to beconstrued as limiting the scope of the invention.

[0074] In the following Examples and Comparative Examples, all “parts”and “%” are by weight unless otherwise noted. Various evaluations inthese Examples and Comparative Examples were made in the mannerdescribed below.

[0075] (1) Average particle size

[0076] It was confirmed by electron microscopical observation that theparticle size of the latex previously synthesized in an emulsified statewas equal to the size of the dispersed particles in the resin, so thatthe size of the dispersed particles in the latex was measured by thelight scattering method using a laser particle size analyzing systemLPA-3100 (mfd. by Otsuka Electronics Co., Ltd.) according to thecumulant method (70 times integration).

[0077] (2) Graft ratio

[0078] Already described above.

[0079] (3) Intrinsic viscosity [η]

[0080] The sample was dissolved in methyl ethyl ketone as the solvent,and the viscosity of the solution was measured by an Ubbellohdeviscometer at 30° C.

[0081] (4) Izod impact strength

[0082] Measured according to ASTM D256 using the notched test specimens,2.5×½×¼ inches.

[0083] (5) Fluidity (melt flow rate)

[0084] Measured according to ASTM D1238 at 240° C. under a load of 10kg. Unit: g/10 min.

[0085] (6) Long-term heat-aging properties

[0086] In the tensile elongation at break test according to ASTM D638,the initial elongation at break and the elongation at break after leftin a 110° C. high-temperature environment for 2,400 hours were measuredto determine retention of elongation at break.

[0087] The component materials used in the Examples and ComparativeExamples are as follows.

[0088] (7) Preparation of component (I)

[0089] Preparation of ABS resin (I-1)

[0090] To a glass-made 7-liter flask equipped with a stirrer, 100 partsof ion exchange water, 1.5 parts of disproportionated sodium rosinate,0.1 part of t-dodecylmercaptan, 40 parts (calcd. as solids) ofpolybutadiene (#0700 produced by JSR Corp.), 15 parts of styrene and 5parts of acrylonitrile were supplied and heated with stirring. At apoint when the temperature reached 45° C., an aqu eous activatorsolution comprising 0.1 part of sodium ethylenediaminetetraacetate,0.003 part of ferrous sulfate, 0.2 part of formaldehyde sodiumsulfoxylate dihydrate and 15 parts of ion exchange water, and 0.1 partof diisopropylbenzene hydroperoxide were added, allowing the reaction tocontinue for one hour. Thereafter, the increment polymerizationmaterials comprising 50 parts of ion exchange water, 1 part ofdisproportionated sodium rosinate, 0.1 part of t-dodecylmercaptan, 0.2part of diisopropyl hydroperoxide, 30 parts of styrene and 10 parts ofacrylonitrile were added continuously over a period of 3 hours tocontinue the polymerization. After completion of the addition, thereaction mixture was further stirred for one hour, then 0.2 part of2,2-methylene-bis-(4-ethylene-6-t-butylphenol) was added, and thereaction product was taken out of the flask. The reaction product(latex) was coagulated with 2 parts of sulfuric acid, washed well withwater and dried at 75° C. for 24 hours to obtain a white powder.Polymerization conversion: 97.2%; graft ratio: 75%; intrinsic viscosity:0.44 dl/g.

[0091] Preparation of ABS resins (I-1-a) to (I-1-d)

[0092] The ABS resins specified in Table 1 were prepared in the same wayas the preparation of the ABS resin (I-1) described above. TABLE 1 ABSresins I-1-a I-1-b I-1-b I-1-b Graft ratio (%) 15 95 50 50 Intrinsicviscosity [η] (dl/g) 0.5 0.5 0.2 0.8

[0093] Preparation of AES resin (I-2)

[0094] To a stainless 10-liter autoclave equipped with a ribbon typestirrer, 20 parts of EPDM [EP-82 produced by JSR Corp.], 55 parts ofstyrene, 25 parts of acrylonitrile and 100 parts of toluene weresupplied, stirred and heated, and the produced rubber-like polymer wascompletely dissolved to obtain a homogeneous solution. Then 0.1 part oft-dodecylmercaptan, 0.5 part of benzoyl peroxide and 0.1 part of dicumylperoxide were added and stirred at 200 rpm while controlling thetemperature to stay constant at 95° C. to carry out polymerization. Thetemperature was raised to 120° C. using one hour after passage of 6hours from start of the reaction, and the reaction was further continuedfor 2 hours and then terminated. The polymerization conversion was 97%.After cooling the reaction mixture to 100 ° C., 0.2 part of2,2-methylene-bis-4-methyl-6-butylphenol was added and then the reactionmixture was taken out from the autoclave and subjected to steamdistillation to remove the unreacted materials and the solvent. Thereaction product was finely ground and supplied to a 40 mmø ventedextruder (220° C., 700 mmHg), whereby the volatiles were substantiallyevaporated away and the polymer was pelletized. Graft ratio: 70%;intrinsic viscosity: 0.42 dl/g.

[0095] Preparation of ASA resin (I-3)

[0096] To a 7-liter glass-made flask equipped with a stirrer, 100 partsof ion exchange water, 1.5 parts of sodium oleate, 0.1 part oft-dodecylmercaptan, 40 parts (calcd. as solids) of acrylic rubber (20LARproduced by Techno-Polymer Co., Ltd.), 15 parts of styrene and 5 partsof acrylonitrile were supplied and heated with stirring. At a point whenthe temperature reached 45° C., an aqueous activator solution comprising0.1 part of sodium ethylenediaminetetraacetate, 0.003 part of ferroussulfate, 0.2 part of formaldehyde sodium sulfoxylate dihydrate and 15parts of ion exchange water, and 0.1 part of diisopropylbenzenehydroperoxide were added and the reaction was continued for one hour.Then the increment polymerization materials comprising 50 parts of ionexchange water, 1 part of sodium oleate, 0.1 part of t-dodecylmercaptan,0.2 part of diisopropylbenzene hydroperoxide, 30 parts of styrene and 10parts of acrylonitrile were added continuously over a period of 3 hoursto carry out the polymerization. After completion of the addition, thereaction mixture was further stirred for one hour, then 0.2 part of2,2-methylene-bis-(4-ethylene-6-t-butylphenol) was added, and thereaction product was taken out from the flask. The reaction productlatex was coagulated with 2 parts of sulfuric acid, washed well withwater and then dried at 75° C. for 24 hours to obtain a white powder.Polymerization conversion: 96.5%; graft ratio: 55%; intrinsic viscosity:0.41 dl/g.

[0097] Preparation of ASS resin (I-4)

[0098] 1.5 part of p-vinylphenylmethyldimethoxysilane and 98.5 parts ofoctamethylcyclotetrasiloxane were mixed and poured into 300 parts ofdistilled water in which 2.0 parts of dodecylbenzenesulfornic acid hadbeen dissolved, and the mixture was stirred for 3 minutes by a homomixerto effect emulsification and dispersion. The mixed solution wastransferred into a separable flask equipped with a condenser, a nitrogeninlet and a stirrer, heated at 90° C. for 6 hours with stirring, andthen cooled at 5° C. for 24 hours to complete the condensation reaction.The condensation rate of the obtained modified polyorganosiloxane was92.8%. The latex of this modified polyorganosiloxane was neutralized topH 7 with a sodium carbonate solution. The average particle size of theobtained modified polyorganosiloxane latex was 2,800 angstroms.

[0099] To a 7-liter glass-made flask equipped with a stirrer, 100 partsof ion exchange water, 1.5 part of sodium dodecylbenzenesulfonate, 0.1part of t-dodecylmercaptan, 40 parts (calcd. as solids) of the saidmodified polyorganosiloxane, 15 parts of styrene and 5 parts ofacrylonitrile were supplied and heated with stirring. At a point whenthe temperature reached 45° C., an aqueous activator solution comprising0.1 part of sodium ethylenediaminetetraacetate, 0.003 part of ferroussulfate, 0.2 part of formaldehyde sodium sulfoxylate and 15 parts of ionexchange water, and 0.1 part of diisopropylbenzene hydroperoxide wereadded and the reaction was continued for one hour. Then the incrementpolymerization materials comprising 50 parts of ion exchange water, 1part of sodium dodecylbenzenesulfonate, 0.1 part of t-dodecylmercaptan,0.2 part of diisopropyl hydroperoxide, 30 parts of styrene and 10 partsof acrylonitrile were added continuously over a period of 3 hours tocarry out the polymerization. After the end of the addition, the mixturewas further stirred for one hour, then 0.2 part of2,2-methylene-bis-(4-ethylene-6-t-butylphenyl) was added, and thereaction product was taken out from the flask. The produced latex wascoagulated with 2 parts of calcium chloride, washed well with water andthen dried at 75° C. for 24 hours to obtain a white powder.Polymerization conversion: 97.2%; graft ratio: 90%; intrinsic viscosity:0.47 dl/g.

[0100] Preparation of component (II) (II-1 to II-5)

[0101] To a 7-liter glass-made flask equipped with a stirrer, 300 partsof ion exchange water, 1.5 part of sodium oleate, 0.1 part oft-dodecylmercaptan and a monomer shown in Table 2 were supplied andheated with stirring. At a point when the temperature reached 45° C.,0.8 part of potassium persulfate and 0.2 part of acidic sodium sulfitewere added and the reaction was continued for 3 hours. The reactionmixture was further stirred for one hour, then 0.2 part of2,2-methylene-bis-(4-ethylene-6-t-butylphenyl) was added and thereaction product (latex) was taken out from the flask. The producedlatex was coagulated with 2 parts of sulfuric acid, washed well withwater and then dried at 75° C. for 24 hours to obtain a white powder.TABLE 2 Thermoplastic resin II-1 II-2 II-3 II-4 II-5 Monomer composition(parts) Styrene 88 83 80 73 50 Acrylonitrile 12 17 20 17 20Methylmethacrylate — — — 10 30 Polymerization conversion (%) 97.2 97.897.7 97.5 97.8 Intrinsic viscosity [η] (dl/g) 0.30 0.37 0.45 0.35 0.33

[0102] Preparation of component (III)

[0103] The following polycarbonate resins produced by MitsubishiEngineering-Plastics Corporation were used:

[0104] III-1: IUPIRON H2000

[0105] III-2: NOVAREX 7022PJ

[0106] Preparation of component (IV)

[0107] The following materials were used.

[0108] Phenol type 1:2[1-(2-hydroxy-3,5-di-t-pentylphenyl)-ethyl]-4,6-di-t-pentylphenyl acrylate

[0109] Phenol type 2:4,4′-butylidene-bis(6-t-butyl-m-cresol)

[0110] Phosphorus type 1:tris(2,4-di-t-butylphenyl) phosphite

[0111] Phosphorus type 2: sodium dihydrogenphosphate

[0112] Sulfur type 1:pentaerythritol-tetrakis-(3-laurylthiopropionate)

[0113] Sulfur type 2:didodecyl 3,3′-thiobispropionate

[0114] Preparation of comparative materials for component (II) (C-1 toC-4)

[0115] To a 7-liter glass-made flask equipped with a stirrer, 300 partsof ion exchange water, 1.5 part of sodium oleate, 0.1 part oft-dodecylmercaptan and a monomer shown in Table 3 were supplied andheated with stirring. At a point when the temperature reached 45° C.,0.8 part of potassium persulfate and 0.2 part of acidic sodium sulfitewere added and the reaction was continued for 3 hours. The reactionmixture was further stirred for one hour, then 0.2 part of2,2-methylene-bis-(4-ethylene-6-t-butyphenyl) was added and the reactionproduct (latex) was taken out from the flask. The produced latex wascoagulated with 2 parts of sulfuric acid, washed well with water andthen dried at 75° C. for 24 hours to obtain a white powder. TABLE 3Comparative thermoplastic resin C-1 C2 C-3 C-4 Monomer composition(parts) Styrene 75 95 83 83 Acrylonitrile 25 5 17 17 Polymerizationconversion (%) 97.5 97.3 97.4 97.8 Intrinsic viscosity [η] (dl/g) 0.300.37 0.25 0.65

EXAMPLES 1 TO 22 AND COMPARATIVE EXAMPLES 1 TO 13 (Preparation ofthermoplastic resin compositions)

[0116] The components (I) and (II) and the comparative polymers weremelted and kneaded by an extruder at the percentages shown in Tables 4to 8 and at 250° C., and injection molded to make the evaluationsamples. Tables 4 to 6 show the results of the Examples of the presentinvention, and Tables 7 and 8 show the results of the ComparativeExamples.

[0117] As is seen from the results shown in Tables 4 to 8, thethermoplastic resin compositions according to the present inventionshowed magnificent heat-aging properties and also had excellent impactstrength and fluidity. It is seen that by using a thermoplastic resin(II) containing acrylonitrile in a specified amount range, as explainedin Examples 1 to 22, it is possible to remarkably improve heat-agingproperties without impairing the other properties.

[0118] In contrast, the resin compositions of Comparative Examples 1 to7, where the thermoplastic resin (II) of the present invention was notused, are very poor in heat-aging properties. Particularly inComparative Example 5 where the acrylonitrile content in thethermoplastic resin (II) was very small and in Comparative Example 6where the intrinsic viscosity of the resin (II) was very low, theproduced resin compositions are low in Izod impact strength, too. It isto be also noted that in Comparative Example 7 where the intrinsicviscosity of the thermoplastic resin (II) was excessively high, theobtained resin composition was low in fluidity.

[0119] Also, in the Comparative Examples where although thethermoplastic resin (II) of the present invention was used the contentsof the resin (II) and the polycarbonate resin (III) were outside thedefined range of the present invention, the produced resin compositionswere poor in heat-aging properties, the product of Comparative Example 8being also poor in fluidity and the products of Comparative Examples 9and 10 being low in Izod impact strength, too.

[0120] Further, in Comparative Examples 11 to 13 where it was attemptedto improve heat-aging properties only by the addition of a heat-agingresistor, there was obtained almost no improving effect, even if theaging resistor was added in large quantities, which indicates that theattempts to improve heat-aging properties by such means are inexpedient.TABLE 4 Example Example Example Example Example Example Example ExampleComposition (parts) 1 2 3 4 5 6 7 8 Component (I): I-1 30 — — — — — — —I-2 — 30 — — 30 30 30 30 I-3 — — 30 — — — — — I-4 — — — 30 — — — —Component (II): II-1 — — — — 10 — — — II-2 10 10 10 10 — — — 10 II-3 — —— — — 10 — — II-4 — — — — — — 10 — Component (III): III-1 — — — — — — —60 III-2 60 60 60 60 60 60 60 — Component (IV) — — — — — — — —Acrylonitrile content 6.2 9.2 6.2 6.2 8.7 9.5 9.2 9.2 in the composition(%) Properties Izod impact strength 60 55 45 48 52 55 48 47 (kgf.cm/cm)Fluidity (g/10 min) 45 42 37 40 43 42 39 55 Long-term heat-aging 60 8682 84 65 58 58 85 characteristics (%)

[0121] TABLE 5 Example Example Example Example Example Example ExampleComposition (parts) 9 10 11 12 13 14 15 Component (I): I-1 — — — — — 1530 I-2 25 20 30 30 30 15 — Component (II): II-1 — — — — — — — II-2 5 3010 10 10 10 10 Component (III): III-1 — — — — 30 — — III-2 70 50 60 6030 60 60 Component (IV): Phenol type 1 — — 0.1 — — — 0.5 Phenol type 2 —— — 0.1 — — — Phosphorus type 1 — — 0.1 — — — 0.5 Phosphorus type 2 — —— 0.1 — — — Sulfur type 1 — — 0.1 — — — 0.5 Sulfur type 2 — — — 0.1 — —— Acrylonitrile content 7.1 10.1 9.2 9.2 9.2 7.7 6.2 in the composition(%) Properties Izod impact strength 65 40 51 50 51 58 45 (kgf.cm/cm)Fluidity (g/10 min) 32 58 45 44 47 43 52 Long-term heat-aging 60 80 9290 85 72 82 characteristics (%)

[0122] TABLE 6 Example Example Example Example Example Example ExampleComposition (parts) 16 17 18 19 20 21 22 Component (I): I-1 — — — — 1045 30 I-1-a 30 — — — — — — I-1-b — 30 — — — — — I-1-c 30 — — — I-4-d — —— 30 — — — Component (II): II-2 10 10 10 10 20 5 — II-5 — — — — — — 10Component (III): III-1 — — — — — — — III-2 60 60 60 60 70 50 60Component (IV) — — — — — — — Acrylonitrile content 6.2 6.2 6.2 6.2 4.97.6 6.5 in the composition (%) Properties Izod impact strength 37 38 3760 30 48 36 (kgf.cm/cm) Fluidity (g/10 min) 46 44 52 36 38 42 43Long-term heat-aging 61 59 60 62 80 58 60 characteristics (%)

[0123] TABLE 7 Comp. Comp. Comp. Comp. Comp. Comp. Comp. Composition(parts) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6Example 7 Component (I): I-1 30 — — — — — — I-2 — 30 — — 30 30 30 I-3 —— 30 — — — — I-4 — — — 30 — — — Component (II): (Comparative component)C-1 10 10 10 10 — — — C-2 — — — — 10 — — C-3 — — — — — 10 — C-4 — — — —— — 10 Component (III): III-1 — — — — — — — III-2 60 60 60 60 60 60 60Component (IV) — — — — — — — Acrylonitrile content 7.0 10.0 7.0 7.0 8.09.2 9.2 in the composition (%) Properties Izod impact strength 51 45 3741 15 21 40 (kgf.cm/cm) Fluidity (g/10 min) 40 37 38 39 38 70 25Long-term heat-aging 7 23 21 20 30 45 45 characteristics (%)

[0124] TABLE 8 Comp. Comp. Comp. Comp. Comp. Comp. Composition (parts)Example 8 Example 9 Example 10 Example 11 Example 12 Example 13Component (I): I-1 — — — — — 30 I-2 37 10 40 30 30 — Component (II):II-1 — — — — — — II-2 3 40 30 — — — Comparative Component C-1 — — — 1010 10 Component (III): III-1 60 — — — — — III-2 — 50 30 60 60 60Component (IV): Phenol type 1 — — — 0.1 1 1 Phenol type 2 — — — — — —Phosphorus type 1 — — — 0.1 1 1 Phosphorus type 2 — — — — — — Sulfurtype 1 — — — 0.1 1 1 Sulfur type 2 — — — — — — Acrylonitrile content 9.89.3 15.1 10.0 10.0 7.0 in the composition (%) Properties Izod impactstrength 38 15 20 43 40 48 (kgf.cm/cm) Fluidity (g/10 min) 26 65 72 3845 46 Long-term heat-aging 23 45 28 24 24 8 characteristics (%)

What is claimed is:
 1. A thermoplastic resin composition with excellentlong-term heat-aging properties, comprising: (I) 10 to 45% by weight ofa rubber-modified thermoplastic resin obtained by graft polymerizing atleast one monomer selected from the group consisting of aromatic vinylcompounds, vinyl cyanide compounds and other vinyl monomerscopolymerizable therewith in the presence of a rubber-like polymer, thegraft ratio of the polymerizate being 10 to 100% and the intrinsicviscosity η of the methyl ethyl ketone solubles at 30° C being 0.2 to0.8 dl/g; (II) 5 to 30% by weight of a thermoplastic resin obtained bycopolymerizing the monomers comprising an aromatic vinyl compound, avinyl cyanide compound and optionally other vinyl monomercopolymerizable therewith, the weight ratio of aromatic vinylcompound/vinyl cyanide compound/other vinyl monomer being50-90/10-20/0-30, and the intrinsic viscosity η of the methyl ethylketone solubles at 30° C. being 0.3 to 0.6 dl/g; and (III) 50 to 70% byweight of a polycarbonate resin, the total amount of (I), (II) and (III)being 100% by weight, and the content of the vinyl cyanide compound inthe whole produced composition being 3 to 12% by weight.
 2. Athermoplastic resin composition according to claim 1 , wherein theweight ratio of aromatic vinyl compound/vinyl cyanide compound/othervinyl monomer of (II) thermoplastic resin is 72-85/15-18/0-10.
 3. Athermoplastic resin composition according to claim 1 , wherein theintrinsic viscosity η of (II) thermoplastic resin is 0.35 to 0.4.
 4. Athermoplastic resin composition according to claim 1 , wherein therubber-like polymer is at least one substance selected from the groupconsisting of ethylene-propylene rubber,ethylene-propylene-nonconjugated diene rubber, acrylic rubber andsilicone rubber.
 5. A thermoplastic resin composition according to claim4 , wherein the rubber-like polymer is ethylene-propylene rubber,ethylene-propylene-nonconjugated diene rubber or mixture thereof.
 6. Athermoplastic resin composition according to claim 1 , which furthercomprises (IV) 0 to 2% by weight of a heat-aging resistor, based on 100%by weight of total amount of (I), (II), (III) and (IV).
 7. Athermoplastic resin composition according to claim 6 , wherein theamount of (I) rubber-modified thermoplastic resin is not less than 10%and less than 45% by weight and the amount of (IV) heat-aging resistoris more than 0% and not more than 2% by weight based on 100% by weightof total amount of (I), (II), (III) and (IV).
 8. A thermoplastic resincomposition according to claim 6 , wherein the heat-aging resistor (IV)is a three-type mixture comprising a phenol type, a phosphorus type anda sulfur type.